I have a 135g fowlr with a 55g sump bubble mag skimmer nac6 4 1500 *hydor koralia pumps. 1800gpm damned mag drive and about 200lbs of rock. I have had the tank for about a year and about a month ago my buddy took down his tank and he gave me his tomato clown. Now this past weekend I noticed that there are at least 5 missing fish. The list includes 3 clowns I blue throat wrasse 1 hippo tang dwarf angel, and 1 fire fish. The list of dish that are still alive are leapord wrasse spotted foxface, cleaner wrasse yellow tang, squirrel fish tomini tang, 2 blue damsels 1 blue chromie 1 engineer gobie algae blenny 1 Sally crab a bunch of turbos and small hermits. Now I did see the Sally crab eating the firefish but why would that many die like that. I checked all my water parameters and everything is fine. I do 15-20% water changes a week. I have filter socks and a performer on my return. The only thing that I just removed today was a small crab that you find on the beach under rocks that my son has put in it when we first got the tank. I took him out and qt him for the time being. Non if the fish look sick or anything. Everyone looks happy. I feed once a day. Can someone elaborate. Here is a pic of the tank.